import java.io.BufferedReader;
import java.io.DataInputStream;
import java.io.FileInputStream;
import java.io.InputStreamReader;


public class ComputeAverage {

	public static void main(String[] args) {
		String inputFile = args[0];
		
		try {
    		FileInputStream fstream = new FileInputStream(inputFile);
    		DataInputStream in = new DataInputStream(fstream);
    		BufferedReader br = new BufferedReader(new InputStreamReader(in));
    		
    		String strLine;
    		int lineCount = 0;
    		float sum = 0;
    		while ((strLine = br.readLine()) != null) {
    			sum += Float.parseFloat(strLine);
    			lineCount++;
    		}
    		
    		System.out.format("%.2f\n", (sum / lineCount));
    		
    		in.close();
    		
    	} catch (Exception e) {
    		System.err.println("Error: " + e.getMessage());
    	}
	}
}
